The Houston Dynamo maintained their home-field dominance against a game but depleted DC United squad in Sunday’s MLS Cup semifinal opener, recovering from an early deficit to dominate the second half and ease to a 3-1 victory.

The reigning Eastern Conference champions now are 90 minutes from a repeat and simply must avoid losing by two or more in next weekend’s decider at RFK Stadium. Considering United’s injury issues, Houston is in prime position.

Visiting United lost two key midfielders during the first half at BBVA Compass Stadium but still enjoyed a lead thanks to a goal from rookie sensation Nick DeLeon. But coach Ben Olsen’s club, stung by a controversial refereeing decision as halftime approached, lacked the personnel and energy to hold that advantage against a Dynamo side that’s unbeaten at home and on a historic playoff roll.

A Test of Depth

By halftime, the first leg of the Eastern Conference finals looked more like a reserve league game.

“It’s a little bit of survival of the fittest right now, Olsen told NBC Sports Network as he headed toward the locker room. “Everybody’s so banged up.”

Injuries on both sides, suffered both before and during play, along with a pair of suspensions, turned Sunday’s match into a test of depth and resolve.

DC has adapted brilliantly to the absence of 2011 MLS MVP Dwayne De Rosario, going 6-0-3 since the playmaker hurt his knee in early September. But the level of improvisation United required on Sunday bordered on the surreal. Soccer coaches typically start pondering substitutions at around the hour mark. Olsen used the last of his three changes in the 56th minute.

Playing on one fewer day of rest and already missing De Rosario, goalkeeper Bill Hamid (suspended) and right back Andy Najar (suspended), DC lost its top attacking player, Chris Pontius, to a groin injury in the 12th. Center midfielder Marcelo Saragosa was forced to leave in the 40th and was replaced by fellow Brazilian Raphael Augusto, who was making his MLS debut. Early in the second half, Olsen had to insert Emliano Dudar in relief of center back Brandon McDonald. The Argentine veteran hadn’t played in more than two months.

“It’s a roll of the dice, a lot of this,” Olsen said. “We’ll make it work. We got a group that responds and usually when things don’t go our way we end up getting a result.”

Houston (17-10-11) had its share of adversity as well. Midfield anchor Ricardo Clark (groin), defender Jermaine Taylor (knee) and forward Calen Carr (hamstring) were unavailable, and midfielder Adam Moffat, who scored a scorcher in the quarterfinal win over Sporting Kansas City, was lost in the 25th.

The Dynamo would win the battle of roster depth. Hainault, who started in place of Taylor, and Giles Barnes, who came on for Moffat, would score the first two goals. Midfielder Luiz Camargo, on for Clark, set up the third.

“It’s a group effort,” Houston captain Brad Davis said last week. “If any of those guys can’t go for any reason we have guys who step in and have to do the job. It doesn’t change. … We have to step on the field still and do a job and do it well.”

Dynamic DeLeon

The rookie whose goal eliminated the New York Red Bulls came through again on Saturday. DeLeon announced his presence when he set up Lewis Neal (Pontius’ replacement) for an open look in the 17th. Ten minutes later, he lifted United to a stunning lead.

Lionard Pajoy raced onto a pass down the left wing, turned toward goal and ripped a shot past goalkeeper Tally Hall and off the post. The ball caromed out to DeLeon, who was alert and composed. The University of Louisville product sent his one-timer off Hainault and in for his eighth goal of the season.

United (18-11-8) didn’t bunker in despite its threadbare roster and troubling history in Houston (0-8-1 all time) and could have scored again. Branko Boskovic nearly connected on a 36th-minute volley and Pajoy saw his 66th-minute effort cleared off the goal line by Dynamo defensive stalwart Bobby Boswell.

But DC’s effort went unrewarded and as the game wore on, Houston gathered its strength and pressed its advantage. United’s fitness and organization would begin to fail.

The breakthrough

Hainault was fortunate to be on the field. His takedown of Augusto in first-half stoppage time appeared to be the sort of denial of an obvious goal-scoring opportunity that should result in a red card. But the play went unpunished (United assistant Pat Onstad was ejected for arguing the call) and sure enough, Hainault would score the Dynamo’s opener.

It came six minutes into the second half on a quick free kick that demonstrated Houston’s tactical acumen. With half the United players still getting organized in the penalty area, Oscar Boniek Garcia was sprung on the left and hit a cross that Hainault finished easily.

In the 68th minute, Barnes beat DC’s Dejan Jakovic – a center back – in the left corner and hit a cross that United goalkeeper Joe Willis deflected out front. Will Bruin was there to slide it off the post for his fourth goal of the postseason.

Defender Kofi Sarkodie gave Houston a priceless two-goal advantage in the 81st. Augusto struggled to clear a corner kick from Davis and Camargo was there to settle the ball and free Sarkodie on the right. The U.S. Under-23 national teamer ripped his shot past Willis.

Following the match, Olsen was irate about the first-half call from referee Ricardo Salazar that could have left his team a man up.

"Everybody in the stadium, everybody on our bench, everybody on their bench, everybody at home saw that it’s a red card,” the DC coach told The Washington Post before adding, "We gave up some soft goals, some concentration lapses, mistakes that we haven’t had in a while. So that’s concerning."

Said Houston manager Dominic Kinnear, "Wonderful second half by us. Great character to come back.”

Looking ahead

United has enjoyed a home-field advantage as well, going 12-1-4 this season at RFK Stadium. But mere victory won’t be enough next Sunday – they’ll have to win by two to force 30 minutes of overtime.

“This game is about survival,” Olsen said this week. “Then we get a week to regroup and get everybody back. I think (the second) game will a much more free-flowing, entertaining game.”

That likely will be possible only if Pontius can play and, perhaps, if De Rosario is ready to make a dramatic return against his former club. Fifth-seeded Houston was able to defend a two-goal lead in the quarterfinal decider at full-strength Sporting Kansas City. Beleaguered DC will have difficulty posing that sort of challenge next weekend, leaving Kinnear and his experienced side liking their chances to advance to a second straight MLS Cup final.